...when you're not even fully using the credit they've given you??
For example, I had a credit card that had a limit of £2,500. I only used at the most maybe up to £300, and then I'd pay it all back when it was due.
The credit card company sent me a letter and said they were really happy with how I was managing my credit card and that they planned to increase my credit limit further.
WHY? When I wasn't using the £2,500.